Turbine apparatus



Oct. 3, 19 50 z f ws-r 2,524,724

- TURBINE APPARATUS Filed Oct. 7, 1948 ATTORNEY Patented Oct. 3, 1950 TURBINE APPARATUS Eric ,A. Zetterquist, Drexel Hill, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa, a corporation of Pennsylvania Application {)ctober '7, 1948, Serial No. 53,239

2 Claims, 1

The invention relates to steam turbines having high and low-pressure dummies and it has for an object to provide for the substitution of steam, which has undergone expansion in the turbine, for that exhausting from the high-pressure or inner dummy and for the application of the steam so substituted to the low-pressure or outer dummy, thereby making possible exposure of the high-pressure cylinder end and gland to more moderate temperature conditions.

A further object of the invention is to provide high and low-pressure dummies wherein the high-pressure dummyis divided into first and second sections with the space between the sections connected to an interstage pressure point higher than the turbine exhaust pressure and with the space between the second section of the high-pressure dummy and the low-pressure dummy connected to an interstage pressure point of higher pressure than the first interstage pressure point so that nozzle discharge steam exhausting from the high-pressure dummy is constrained to flow to the interstage pressure point of lower pressure and steam from the interstage pressure point of higher pressure, and which has done work in the turbine blading, flows through the low-pressure dummy, in place of impulse nozzle discharge steam, to lower the temperature to which the high-pressure end of the turbine is subjected.

The foregoing and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

turbine having the improvement applied thereto; and

Fig. 2 is an enlarged detail view of the dummy arrangement.

In the drawing, there is shown a turbine having a cylinder It! and a rotor H. The cylinder has an interior structure [2 at the high-pressure end formed with one or more nozzle chambers l4 furnished with steam in the usual way and each of which has nozzles It for discharging steam at high velocity for action on impulse blading I6 carried by the cylinder and by the rotor.

Steam exhausting from the impulse blading l6 undergoes progressive expansion, with energy abstraction, in the blade groups l1, 18, I9 and 20, after which it enters the turbine exhaust space 2|.

The blade groups each include a plurality of stages of stationary and moving blade rows. The

stationary blade rows of the groups are respectively carried by blade rings 24, 25, and 21 supported interiorly of the cylinder l0.

High and low-pressure dummies, at 28 and at 29, at the high-pressure end of the turbine balance the blading steam thrust. The highpressure dummy, at 28, includes ring sections as and 3! carried by the cylinder, a piston 32 carried by the rotor, labyrinth packing 33 carried by the ring section 3!! and by the piston, and labyrinth packing 3d carried by the second ring section 3! and by the rotor. As shown, the first ring section 3!] is preferably constituted by an inward radial continuation of a nozzle ring of the nozzle chamber ring structure I 2.

The low-pressure dummy, at 29, is comprised by a ring 35 carried by the cylinder, a piston 36 carried by the rotor and arranged adjacent to the piston 32, and labyrinth packing 31 interposed between the ring and the piston, the ring 35 and the piston 36 being respectively larger than either of the ring sections and 3! and the piston 32. The second ring section3l of the high-pressure dummy is carried by the lowpressure dummy ring by means of a connecting radial web 38.

The turbine exhaust space 2! and the, lowpressure dummy exhaust space 39 are connected by the equilibrium pipe iii). The space 42 between the ring sections Sil'and SI of the highpressure dummy are connected by a passage 43 to a suitable interstage pressure point of the turbine/for example, between the blade rings 26 and 2t and the space 44 between the second blade ring section and the ring 35 0f the lowpressure dummy is connected by a passage 45 to an interstage pressure point of higher pressure than the first interstage pressure point, for example, the pressure point between the blade rings 25 and 26.

Designating the successively lower pressures of steam discharging from the nozzles and from the blade ring groups, as P1, P2, P3, and P4 and P5, P5 being the turbine exhaust pressure, it will be apparent that the pressure difierence, P1 minus P4, acts across the first ring section 30 of the high-pressure dummy, the pressure difference, P3 minus P4, is effective across the second ring section 3! of the high-pressure dummy in a direction opposed tothat of the pressure difference across the first ring section 30, and the pressure difference, P3 minus P5, acts across the low-pressure dummy.

Steam approaching the mean temperature between that in the impulse chamber and that in the exhaust space is drawn by the interstage leakoff passage as to the low-pressure dummy, to the equilibrium pipe 40, and to the gland packing. A portion of such steam enters the space 44 from the interstage leak-01f passage and flows in the opposite direction through the second section of the high-pressure dummy. As the latter section is subjected to a relatively small pressure drop (P3 minus P4), only a small number of labyrinth sealing strips or packing strips is required. Impulse chamber discharge nozzle steam leaks past the first section of the high-pressure dummy, and the combined leakage into the space 42 at reduced temperature is supplied to the turbine flow passage by the connection 43.

As contrasted to the conventional construction, in which nozzle discharge steam flows in series through the packing of the high and low-pressure dummies, the temperature at the exhaust end. of the low-pressure dummy may be substantially reduced by the introduction of interstage leak-off steam to constrain the nozzle discharge steam exhausting from the first ring section of the highpressure dummy to fiow to the turbine flow path and thereby to take the place of nozzle discharge steam acting across the low-pressure dummy. For a throttle pressure of 1250 pounds and a temperature of 925, an impulse nozzle discharge pressure of 700 pounds, and an exhaust pressure of 50 pounds, the reduction in temperature at the exhaust end of the low-pressure dummy may be of the order of 250.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What I claim is:

1. In a turbine, the combination of, a cylinder; a rotor; means carried by the cylinder and provided with a nozzle chamber; impulse blading including blading carried by the rotor; a plurality of stages of stationary rows of blades carried by the cylinder and of moving rows of blades car ried by the rotor and arranged in the turbine flow path between the impulse blading and the turbine exhaust space; a high-pressure dummy including first and second ring sections carried by the cylinder, a piston carried by the rotor, and packing interposed between each of the ring sections and the piston; a low-pressure dummy including a ring carried by the cylinder, a piston carried by the rotor, and packing interposed between the ring and the piston; a passage connected to an interstage pressure point along the turbine flow path for conducting to the latter steam exhausting from the first ring section of the highpressure dummy; a passage for conducting steam from the turbine flow path at an interstage point of higher pressure than the first interstage point to the space between the second section of the high-pressure dummy and the low-pressure dummy; and a passage connecting the exhaust space of the low-pressure dummy and the turbine exhaust space.

2. In a turbine, the combination of, a cylinder; a rotor; means carried by the cylinder and provided with one or more nozzle chambers; impulse blading including blading carried by the rotor; a plurality of blade groups arranged in the turbine flow path between the impulse blading and the turbine exhaust space; each of the blade groups including rows of stationary blades and cooperating moving rows of blades carried by the rotor; blade rings carrying the stationary blades of the respective groups and supported interiorly of the cylinder; a high-pressure dummy including a first and second ring sections carried by the cylinder, a piston carried by the rotor, and packing interposed between each of the ring sections and the piston; a low-pressure dummy including a ring carried by the cylinder and connected by a radial web to the high-pressure dummy second ring section to support the latter, a piston, and packing interposed between the ring and the piston; said low-pressure dummy ring and piston being of larger diameter than the high-pressure ring sections and piston and the pistons being contiguous; a passage connected to an interstage pressure point for conducting to the latter steam exhausting from the first ring section of the high-pressure dummy; a passage for conducting steam from an interstage pressure point of higher pressure than No references cited. 

